Polypeptide powders containing medically useful polypeptides and pharmaceutically acceptable carriers or diluents may be prepared for administration by inhalation or otherwise. Inhalable polypeptide powder preparations have been described in WO95/00127 and WO95/00128.
Diluents are commonplace in pharmaceutical preparations, especially in formulations for inhalation. They are used to stabilise various drugs during manufacture and storage and to adjust the amount of powder making up unit doses--in general, powder inhalers are capable of delivering a drug substance with good dose accuracy only for certain dose sizes, while different drugs have different potencies and must therefore be delivered in different amounts. As these amounts are often too small for proper dose accuracy to be ensured, diluents are added to give the desired dose size.
Previously, reducing sugars such as lactose and glucose have been used as diluents in polypeptide powder formulations. These however have a tendency to react with polypeptides and are therefore unsatisfactory.
It is suggested in WO95/00127 and WO95/00128, relating to polypeptide powders for inhalation, that non-reducing sugars such as raffinose, melezitose, lactitol, maltitol, trehalose, sucrose, mannitol and starch may be preferred additives for the polypeptide powders.
It has now been found that melezitose is an exceptionally good diluent compared with other possible non-reducing sugar diluents for polypeptide powder formulations, giving an unexpectedly high respirable fraction of powder when inhaled.